Brachycephaly

Brachycephaly (derived from the Ancient Greek βραχύς, 'short' and κεφαλή, 'head') is the shape of a skull shorter than average in its species. It is perceived as a desirable trait in some domesticated dog and cat breeds, notably the pug and Persian, and can be normal or abnormal in other animal species.
In humans, is can appear both pathologically and non-pathologically as a result of normal human variation. It is particularly common in Mongolians and the Andamanese.
In anthropology, human populations have been characterized as either dolichocephalic (long-headed), mesocephalic (moderate-headed), or brachycephalic (short-headed). The usefulness of the cephalic index was questioned by Giuseppe Sergi, who argued that cranial morphology provided a better means to model racial ancestry.
When pathological, it is known as flat head syndrome, and it results from premature fusion of the coronal sutures, or from external deformation. The coronal suture is the fibrous joint that unites the frontal bone with the two parietal bones of the skull. The parietal bones form the top and sides of the skull. This feature can also be a symptom of Down syndrome.
There are also cases of brachycephaly associated with plagiocephaly. Brachycephaly with plagiocephaly is positional and has become more prevalent since the "Back to Sleep" campaign. The Back to Sleep campaign began in 1994 as a way to educate parents about ways to reduce the risk for sudden infant death syndrome (SIDS). The campaign was named for its recommendation to place healthy babies on their backs to sleep. Placing babies on their backs to sleep reduces the risk for SIDS, also known as "cot death" or "crib death." This campaign has been successful in promoting infant back sleeping and other risk-reduction strategies to parents, family members, child care providers, health professionals, and all other caregivers of infants, at a cost of increasing the incidence of this deformation of the head. It is considered a cosmetic problem. Many pediatricians remain unaware of the issue and possible treatments. Treatments include regular prone repositioning of babies ("tummy time").
Brachycephaly as a desired trait
Brachycephaly also describes a developmentally normal type of skull with a high cephalic index, such as in snub-nosed breeds of dog such as pugs, Shih Tzus, and bulldogs or cats such as the Persian, Exotic and Himalayan. The term is from Greek roots meaning 'short' and 'head'. While being a desirable trait of specific cat and dog breeds, the production and breeding of brachycephalic animals is technically considered as an animal abuse in some legislations. This arises from the fact that animals with significantly shortened skulls frequently develop brachycephalic airway obstructive syndrome, causing them to have difficulties when breathing, suffering from hyperthermia due to insufficient cooling abilities and frequent infections of the cornea and lacrimal glands. Breeding of animals that will have significantly worsened life quality due to anatomical abnormalities is clearly stated to be illegal in some European countries, yet the production of such breeds is still very frequent. Apart from these, brachycephalic pups and kittens also have high prenatal mortality. Attention should be paid to breed standards which promote increased brachycephaly in cats which has the potential to negatively impact their welfare, and potential buyers of brachycephalic cat breeds should be made aware of the risks of their conformation.
Diagnosis
Conditions with brachycephaly
Achard syndrome
Achondrogenesis type II
Acrocephalosyndactyly type I
Acrodysostosis 1 with or without hormone resistance
Acrofrontofacionasal dysostosis
Acromelic frontonasal dysostosis
Acyl-CoA oxidase deficiency
Adenylosuccinate lyase deficiency
Agenesis of the corpus callosum with peripheral neuropathy
ALDH18A1-related de Barsy syndrome
ALG9 congenital disorder of glycosylation
Alveolar capillary dysplasia with pulmonary venous misalignment
Angelman syndrome
Antley-Bixler syndrome
Aspartylglucosaminuria
Autism spectrum disorder due to AUTS2 deficiency
Autosomal recessive faciodigitogenital syndrome
Axenfeld-Rieger anomaly
Bailey-Bloch congenital myopathy
Bardet-Biedl syndrome
CHIME syndrome
Cleidocranial dysplasia, recessive form
Coffin-Siris syndrome
Complete trisomy 21 syndrome
Complex lethal osteochondrodysplasia
Congenital contractural arachnodactyly
Congenital disorder of glycosylation, type iit
Congenital heart defects and ectodermal dysplasia
Cornelia de Lange syndrome
Craniofacial dysplasia-osteopenia syndrome
Craniofrontonasal syndrome
Craniosynostosis-anal anomalies-porokeratosis syndrome
Crouzon syndrome
Crouzon syndrome-acanthosis nigricans syndrome
DeSanto-Shinawi syndrome due to WAC point mutation
Ehlers-Danlos syndrome
Fine-Lubinsky syndrome
Fontaine progeroid syndrome
Frank-Ter Haar syndrome
Frontonasal dysplasia-severe microphthalmia-severe facial clefting syndrome
Frontonasal dysplasia with alopecia and genital anomaly
Gomez-Lopez-Hernandez syndrome
Hallermann-Streiff syndrome
Hereditary spastic paraplegia
Hirsutism-skeletal dysplasia-intellectual disability syndrome
Holoprosencephaly, recurrent infections, and monocytosis
Hypotonia, infantile, with psychomotor retardation and characteristic facies
Intellectual disability-facial dysmorphism syndrome due to SETD5 haploinsufficiency
Intellectual disability-microcephaly-strabismus-behavioral abnormalities syndrome
KBG syndrome
Kleefstra syndrome
Kohlschutter-Tonz syndrome-like
Larsen-like syndrome, B3GAT3 type
Lethal occipital encephalocele-skeletal dysplasia syndrome
Lethal osteosclerotic bone dysplasia
Mandibuloacral dysplasia progeroid syndrome
MEGF8-related Carpenter syndrome
Methylmalonic acidemia with homocystinuria, type cblX
MGAT2-congenital disorder of glycosylation
Microbrachycephaly-ptosis-cleft lip syndrome
Microcephaly, facial dysmorphism, renal agenesis, and ambiguous genitalia syndrome
Microphthalmia with brain and digit anomalies
MOMO syndrome
Muenke syndrome
Neonatal pseudo-hydrocephalic progeroid syndrome
Oculodentodigital dysplasia, autosomal recessive
Osteogenesis imperfecta
Osteosclerosis, Stanescu type
Phosphoribosylaminoimidazole carboxylase deficiency
Pontocerebellar hypoplasia
Potocki-Shaffer syndrome
RAB23-related Carpenter syndrome
Radial aplasia-thrombocytopenia syndrome
Renpenning syndrome
Ritscher-Schinzel syndrome
Saethre-Chotzen syndrome
Smith-Magenis syndrome
Spastic paraplegia, intellectual disability, nystagmus, and obesity
Spondyloepimetaphyseal dysplasia, Genevieve type
SRD5A3-congenital disorder of glycosylation
Trigonocephaly-bifid nose-acral anomalies syndrome
Weill-Marchesani syndrome
Treatment
Brachycephaly can be corrected with a cranial remolding orthoses (helmet) which provide painless total contact over the prominent areas of the skull and leave voids over the flattened areas to provide a pathway for more symmetrical skull growth. Treatment generally takes 3–4 months, but varies depending on the infant's age and severity of the cranial asymmetry.
However, studies by scientists in the Netherlands investigating helmet therapy on mild to moderate cases of brachycephaly have found there was no significant difference over time between infants treated with helmets and infants left untreated. All parents of infants treated with helmets confirmed negative side effects including skin irritation and sweating.
The study was criticised by the American Orthotic & Prosthetic Association in a letter to the New York Times. The letter noted that the study focused only on mild to moderate cases, saying that helmet treatment may still be useful for more severe cases. The letter also criticised the low participation rate (21%) of the randomized study, and noted that the incidence of fitting issues in the study, at 73%, "seems very high".
See also
Artificial cranial deformation
Cephalic index
Craniosynostosis
Dolichocephaly
Plagiocephaly
Safe to Sleep
References
External links
NINDS – Cephalic Disorders Overview
Brachycephalic Official Website
Congenital disorders of musculoskeletal system
Hereditary dog diseases